Segment Information - Generation Total Revenues Net of Purchased Power and Fuel Expense (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Segment Reporting Information [Line Items]
Total RNF for Reportable Segments	$ 2,298	$ 1,941
Other	446	(105)
Total RNF	2,744	1,836
Mid-Atlantic
Segment Reporting Information [Line Items]
Total RNF for Reportable Segments	674	691
Midwest
Segment Reporting Information [Line Items]
Total RNF for Reportable Segments	703	689
New York
Segment Reporting Information [Line Items]
Total RNF for Reportable Segments	344	261
ERCOT
Segment Reporting Information [Line Items]
Total RNF for Reportable Segments	209	52
Other Power Regions
Segment Reporting Information [Line Items]
Total RNF for Reportable Segments	368	248
Operating Segments
Segment Reporting Information [Line Items]
Total RNF for Reportable Segments	2,316	1,946
Operating Segments | Mid-Atlantic
Segment Reporting Information [Line Items]
Total RNF for Reportable Segments	675	722
Operating Segments | Midwest
Segment Reporting Information [Line Items]
Total RNF for Reportable Segments	700	690
Operating Segments | New York
Segment Reporting Information [Line Items]
Total RNF for Reportable Segments	329	225
Operating Segments | ERCOT
Segment Reporting Information [Line Items]
Total RNF for Reportable Segments	220	53
Operating Segments | Other Power Regions
Segment Reporting Information [Line Items]
Total RNF for Reportable Segments	392	256
Intersegment Revenues
Segment Reporting Information [Line Items]
Total RNF for Reportable Segments	(18)	(5)
Other	(18)	(5)
Intersegment Revenues | Mid-Atlantic
Segment Reporting Information [Line Items]
Total RNF for Reportable Segments	(1)	(31)
Intersegment Revenues | Midwest
Segment Reporting Information [Line Items]
Total RNF for Reportable Segments	3	(1)
Intersegment Revenues | New York
Segment Reporting Information [Line Items]
Total RNF for Reportable Segments	15	36
Intersegment Revenues | ERCOT
Segment Reporting Information [Line Items]
Total RNF for Reportable Segments	(11)	(1)
Intersegment Revenues | Other Power Regions
Segment Reporting Information [Line Items]
Total RNF for Reportable Segments	(24)	(8)
Segment Reconciling Items
Segment Reporting Information [Line Items]
Other	$ 428	$ (110)